multibuttonentry: Fix item resource clean up logic.

multibuttonentry: Fix item resource clean up logic.

Summary:
There are four cases where items are deleted.

1. Select item and push back button.
2. Delete "X" part of item.
3. Calling elm_object_item_del().
4. MBE deleted.

Previous logic is can't support for all cases.

below problems were there.

eina_list_remove() called twice.
list data free twice.

@fix

Test Plan: elementary_test -> multibuttonentry test.

Reviewers: jpeg, cedric

Subscribers: cedric, jpeg

Differential Revision: https://phab.enlightenment.org/D5030